In a long-term evolution advanced (LTE-A) system, a coordinated multi-point (CoMP) transmission technology is introduced to enhance performance of a cell-edge user, and improve an average throughput of the cell at the same time.
In LTE-A Rel. 11, a downlink CoMP technology is standardized for joint transmission (JT), dynamic point selection and coordinated scheduling/beamforming. In order to accurately perform link adaptive transmission and effectively obtain a gain of the CoMP transmission, UE needs to accurately feed back for different transmission assumptions.
As the UE is limited in an actual processing ability, the number of pieces of channel state information (CSI) reported by the UE is limited. In the CoMP transmission, as multiple pieces of CSI corresponding to different transmission points and interference assumptions need to be reported, there is no effective method for reporting CSI at present for the CoMP transmission.